In the course of providing healthcare to patients, vital statistics and other patient parameters are monitored. Different types of patient monitoring devices are able to monitor physiological state of the patient via at least one electrode that is coupled to the skin of a patient at various locations on the body. For example, the electrical activity of the heart is routinely monitored in clinical environments using an electrocardiogram (ECG) monitor. The ECG monitor is connected to the patient by a plurality of electrodes that monitor the electrical impulses of the patient's heart. In order for the ECG monitor to effectively record the electrical impulses of a patient, electrodes extending therefrom conventionally include a conductive gel that is embedded in an adhesive pad used to secure the electrode to the body of a patient. Wires from the monitor are selectively connected to the electrode in order to communicate voltages detected to the ECG monitoring device to provide a healthcare practitioner with data regarding the patient's heart function.
The quality of the recorded signal depends on the electrical resistance between the electrode and the patient's body (i.e., patient skin). The resistance at the electrode-patient interface is known as contact impedance. Contact impedance can vary due to a number of factors such as electrode gel drying, skin moisture level, or loss of secure contact between an electrode and the patient's skin. Measurements to determine the contact impedance at various times while the patient is being monitored can ensure that the signal being monitored is of a sufficient quality.